The invention relates to a method for analyzing amount of activity due to radioactive seeds having specified nominal activities and that are to be implanted in animal tissue.
In the field of implanting radioactive seeds in an animal body the American Association of Physisists in Medicin (AAPM) is recommanding in TG 43 that of each badge of seeds used for the treatment of a patient at least 10% be independently measured. In case the seeds are to be implanted in a manual procedure the seeds are delivered to the hospital in a non-sterile form. The hospital physicist is required to measure at random 10% of the seeds delivered before sterilization to confirm the activity level of the seeds in the badge. In known automated procedures seeds are delivered in a sterile form, however, no solution has been described so far of measuring at random the seeds of a badge without breaking sterility of the sterile delivered seeds.
A device for manually implanting radioactive seeds in an animal body is known from Journal of Brachytherapy International 1998;14:21-27. Therein is described a device in which under ultrasound guidance using an ultrasound probe and using a first template implant needles, hereinafter needles, are placed in a prostate gland. Under fluoroscopy the positions of the needles are checked. For every individual needle the length of the train of seeds is determined. The trains of seeds are placed into the needles with custom-made stylets. Thereafter a second template is attached to a stepping unit in the same way as the ultrasound probe. The ends of the stylets are placed in the second template at the same positions as the needles in the first template. The correct distance between the second template and the ends of the needles is established and the needles are retracted over the stylets manually.
The described method of implanting is cumbersome in that a lot of specialized and delicate tasks have to be fulfilled manually. Acting like this it is not possible to reach a high degree of accuracy in the placement of the seeds. The determination of the desired placements of the seeds can be done with very high accuracy based upon the known physics of the radioactive radiation emitted by the seeds and the geometry of the prostate gland. Such determination of desired placement usually is done by means of a computer programmed with a known therapy planning program. One such program is marketed under the trademark PLATO by Nucletron BV of the Netherlands. Nevertheless the manual placement of the seeds makes it necessary to recheck the number of seeds introduced and if necessary to introduce additional seed trains.
U.S. Pat. No. 6,129,670 discloses an apparatus for implanting radioactive seeds in a patients"" body. The seeds are present in sterilized cassettes for holding seeds and spacers. The seeds are being described as having one of two different radioactive activity levels. The apparatus comprises means for loading an implant needle with a desired train of seeds and spacers. The apparatus comprises radiation sensing means along the needle at positions where the seed or a spacer may end up when a train of seeds and spacers is being assembled. The radiation detecting means distinguish between no radiation, i.e., a spacer, a first radioactive activity level and a second radioactive activity level. After a needle has been provided with a desired train of seeds and spacers the needle is decoupled from the apparatus and inserted into a convenient storage system for the loaded needles until they are used.
The company South Bay Medical describes a Smart Cartridge which holds a number of pre-sterilized seeds together with spacers, blanks and needle packs.
Neither U.S. Pat. No. 6,129,670 nor South Bay Medical describe how to measure activity of at least 10% of the seeds in a badge without breaking sterility.
It is an object of the invention to provide a method for analyzing amount of activity due to radioactive seeds having specified activities and that are to be implanted in animal tissue comprising the steps of determining a pre-plan comprising determining a desired distribution of implanted of said radioactive seeds and non-radioactive spacers in said tissue, in accordance with said pre-plan assembling trains of said radioactive and said spacers for implantation, accurately determining radiation activity of each seed while adding such seeds to said train with an accuracy that allows distinguishing between different activities within tolerance ranges of said specified activities for such seed.
It is a further object of the invention to provide a method for implanting radioactive seeds having specified activities in animal tissue comprising the steps of determining a pre-plan comprising determining a desired distribution of implanted radioactive seeds and non-radioactive spacers in said tissue, in accordance with said pre-plan assembling trains of seeds and spacers for implantation, determining radiation activity of each seed while adding such seed to a said train, implanting unloaded needles in said tissue, assembling said trains outside said implanted onloaded needles in an assembly unit, connecting said assembly unit to a said implanted unloaded needle before, during or after assembling a said train for such needle, transferring said assembled train from said assembly unit to said implanted unloaded needle and implanting said transferred assembled train in said animal tissue.
It is still a further object of the invention to provide a method for determining a postplan for radiation treatment of animal tissue, said method comprising determining a pre-plan for radiation treatment of said animal tissue based upon specified activities of to be implanted radioactive seeds, in accordance with said pre-plan assembling trains of said seeds and spacers for implantation, determining radiation activity of each seed while adding such seed to a said train and determining said postplan using determined radiation activities.
The invention shall now be described in more detail with reference to the accompanying drawings.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: